Internal combustion engine



sem. 15, 1942.l

J, J. WYDLER INTERNAL COMBUSTION ENGINE Original Filed Nov. l2. 1938 ATT R'NEY INVENTOR fom/wv LW/,01,51%

Patented Sept. 15, 1942 INTERNAL COMBUSTION ENGINE Johann J. Wydier, Westeld, N. J., assignor, by mesne assignments, to Cities Service Oil Company, New York, N. Y., a corporation of Pennsylvania Original application November 12, 1938, Serial No.

240,013. Divided and this 15, 1940, Serial N0. 318,986

application February s claimsf (cl. 12s-.1),l

Y cylinder to keep stratined in the cylinder during This invention relates to internal combustion engines, and more particularly to an improved internal ,combustion engine adapted for emciently and economically converting heat ,of combustion into mechanical work. This invention was originally described in my copending application Serial No. 240,013, led November l2, 1938, for Internal combustion method and apparatus, of which this is a division.

Many suggestions have been heretofore made designed to increase the heat conversion eiliciency of the internal combustion engine. For example it has been heretofore suggested that the heat losses sustained through radiation from the combustion zone might be reduced by lining said zone with refractory or heat insulating material. Likewise i1; has been heretofore proposed to reduce the energy loss normally sustained through discharge of hot engine exhaust gases by employment of a compound engine equipped with a second low pressure expansion cylinder operable to convert some of the energy still carried by the exhaust gases from the high pressure` working cylinder into mechanical energy.

A primary object of the present invention is to provide an improved internal combustion engine which is adapted for eilicient conversion of heat of combustion into mechanical work even when practiced within the connes of a single power cylinder.

Experience has shown that an important contributory cause of the low power conversion secured in the operation of many present day interna1 combustion engines is the ineicient utilization of air and fuel supplied for combustion. For example many fpresent day Diesel engines operate on an air-fuel ratio in which the air exceeds by a considerable amount that theoretically required for .complete combustion of the fuel, and the excess air not utilized for combustion carries away with it from the working space .a considerable 4amount of heat' as waste energy. A reason for the need of this large amount of excess air in order to completely burn the fuel supply has been the inefficient mixing of the fuel and air within the combustion zone prior to and during the working stroke. l

Another object of the present invention is to provide an improved interna1 combustion engine design adapted to reduce power loss due to heat radiation and ineiiicient air utilization.

To accomplish the above object one important feature of the invention contemplates making deliberate use of and promoting the tendency successive piston strokes, which is a primary cause of ineiflcient air utilization by present operating engines, as the basic-feature of an improved six-stroke cycle internal combustion operation adapted for practice with substantially theoretical volumes of air and fuel for complete combustion, andfwith reduced radiation losses.

The improved engine cycle which forms the subject of the present invention may be carried out in one or two working cylinders,r and may employ precompression or air 'supercharging primarily as a means of reducing piston displacement of the power unit. All of the air used during the working cycle enters the main power cylinder during one air intake stroke; However, this air is burned in two portions during two power strokes of `a six-stroke cycle. A major part but not all of the fuel for one complete cycle, is supplied and burned during the rst power stroke. That portion of the air which is to be burned during the second power stroke is first introduced to the engine cylinder as substantially pure cold. air during the rst part of the air intake stroke, and during the latter part of the air intake stroke the air utilized in the first power stroke is introduced in preformed of gases successively introduced into an engine admixture with the fuel for ,the first power stroke. The air rst introduced forms a stratifled layer adjacent the piston head, and stratiiication is maintained between this air layer and the layer of combustible mixture as the piston reciprocates through the intake and first compression stroke. During the rst power stroke this layer of air adjacent the piston forms an envelope or cushion between the burning portion of the charge and the piston and cylinder walls.

With a properly proportioned mixture -of air and fuel undergoing combustion during the first power stroke, asubstantial part of the heat which would otherwise be lost by radiation and conduction through the walls and piston head is absorbed by the air envelope, and is thereby returned as excess power during the rst power stroke by reason of the expansion of the volume burned portion of the rst air charge is used up in burning a second charge of fuel which may be introduced by solid injection at the end of the second compression stroke.

Special design features of the engine for carrying out the operating cycle above outlined will be explained in the following specic description. An important design feature resides in the employment of an ignition and valve chamber at the head of the primary working cylinder having a throat of substantial area communicably connecting the chamber with the cylinder bore, whereby to introduce gas into and remove gases from the cylinder while promoting conditions of gas stratincation and non-turbulence within the cylinder bore.

With the above and otherl objects and features in view, the invention will be hereinafter particularly described with reference to-the accompanying drawing, in which:

Fig. 1 is a diagrammatic vertical section of an engine showing the piston at bottom dead center position, either just prior to completion of the first and intake stroke of .the six-stroke cycle, or at the end of the rst power stroke, or at the beginning of the second compression stroke;

Fig. 2 is a diagrammatic view showing the engine of Fig. l with the piston at top dead center position 64, either at the end of the second stroke and rst compression stroke of the six-stroke cycle, or at the beginning of the first power stroke;

Fig. 3-is a view in elevation of a preferred design of one cylinder power plant adapted for the practice of the process of the invention, part of inder. a fuel injection nozzle 12 is positioned at the combustion end of the cylinder (Fig. 1), in position to inject atomized fuel under pressure past a valve I3 into chamber 66 and clearance space 62. According to the preferred plan of operation, as practiced in one cylinder, the fuel ine jection nozzle 12 is. only operated at the beginning of the second power stroke.

Referring to Fig. 3, it will be seen that all of the air for both power strokes is preferably precompressed in compressor 54, the compressed air being conducted to the intake valve 68 through pipe 14. The precompressed air is preferably cooled down to substantially atmospheric temperature prior to its introduction to the working cylinder by passage through the coils of an intercooler or.

heat exchanger 56. Water or other cooling liquid is passed through the intercooler by pipe 55. According to the preferredcycle, the-fuel which is used up during the first power stroke is preadmixed in correct proportion for perfect combustion with that portion of the air used up in the rst power stroke, before the air and fuel mixture enters the working cylinder. This preadmixture or precarburetion of the air and fuel used in the first power stroke is effected by a carbureter 16 mounted in the air supply pipes 14, such carbureter having a fuel injection nozzle 18 by which the fuel is atomized into the air stream flowing toward the intake valve 68 during the intake stroke. A valve 11 controls supply of fuel to the nozzle 18.

In Fig. 2 a hot spot ignition cell 80 is shown as ported out into chamber 66 at a point adjacent .the working cylinder and valve chamber and part i of the carbureter being shown in vertical section;

Fig. 4 is a plan section of the cylinder head of the engine of Fig. 3, taken on the line 4- 4 of Fig. 32

Fig. 5 is a diagrammatic vertical section of a preferred design of three-cylinder plant adapted for practicing the process cycle of the invention.

The invention contemplates a plant including a single power cylinder, or two cylinders which may be termed a primary and a secondary cylinder. While the drawing illustrates a power plant in which the cylinders are disposed on a vertical main axis, the cycle can be just as well practised in a -power plant having horizontally disposed cylinders, or having cylinders disposed at any angle to the horizontal.

According to the present invention a complete process cycle develops two power strokes during a period of six piston strokes, and thus may be termed a six-stroke cycle process.

As illustrated in Figs. 1 to Fig. 5, inclusive, the principal elements of a power plant adapted for practicing the process include a working cylinder 60, a piston 58 mounted for reciprocation in the cylinder, and an ignition and valve chamber 66 positioned at the combustion end of the cylinder and communicably connected therewith by a throat 52 having an area which is at least onefourth of the total cross-sectional area of the cylinder. An air and fuel intake valve 68 and an exhaust gas discharge valve 16 are mounted the exhaust valve 10. With this location the cell 80 retains at all times a considerable amount of heat and can function as an ignition element for the air-fuel charge in'the cylinder at the beginning of the rst power stroke.

As shown in Fig. 3, provision is made for watercooling the upper part of the working cylinder and the'ignition and valve chamber. However, water cooling is not absolutely necessary for the cylinder walls if the engine is operated on the preferred cycle of the present invention. A power cylinder suitable for practicing the process of the invention may be operated with a compression ratio in the range 5-8, or in other words is precompressed to a maximum of about 40% of within the chamber 66. The total combustion'.

its original volume, the engine may operate with an overall compression ratio of between 121/2 and 20.

In practicing the cycle in a single cylinder power unit, the air and fuel intake valve 68 is only open during the i'lrst of three engine revolutions making up the cycle. The exhaust valve 10 operates during the second revolution of the engine and again during the third revolution. While not specifically illustrated, it will be understood that the intake and exhaust valves may be suitably actuated and timed from the engine crank shaft.

The complete operating cycle will now be described, as practiced in a single cylinder power unit of the type illustrated in Figs. 1 to 4, inelusive.

Referring to Figs. l and 3, the intake valve 68 remains open during the first stroke of the piston, and the total air charge for a complete cycle is taken in from the cold air supply pipe 14. Normally the first 30%-40% of the air lcharge is taken into the cylinder as clean cold air during the first part of the intake stroke' while the fuel supply to carbureter 18 is cut oi! by a valve 11. During the last part of the intake stroke the balance of the air for the complete cycle is taken in in the form of a preformed fuel-air mixture, the fuel being introduced into the air at the carburetor 16. By thus admitting the air for both power strokes in successive periods of the intake stroke, the gases within the cylinder with the piston 58 in the position shown in Fig. 1, will con-1 sist of a stratum of pure cold air above the piston and below the imaginary dividing line 8l, while that part of the cylinder lying above the dividing line 88 is filled with an air-fuel mixture, the components of which are in substantially theoretically correct proportions for perfect combustion during the first power stroke. y

While some stratification of successively introduced volumes of gases within the cylinder of a high speed engine might be expected from normal operating experience, the engine of the present invention is designed to promote and assure such stratification by providing an ignition and valve chamber 66 at the combustion end of the cylinder having sufficient volume to make up the major part -of the desired clearance space, and by providing a throat 52 of substantial area, i, e., at least one-fourth the area'of the cylinder, communicably connecting such combustion space with the cylinder proper. By this construction any air or air-fuel mixturewhich is admitted past th'e inlet valve 68 at high velocity is forced to spread out in all directions within the valve chamber 66 across the whole width of the cylinder bore. In doing so the rate of iiow is slowed down in amount inversely proportional to the increase of cross-sectional area of flow within the chamber. By that time any kinetic or inertia energy which might h'ave been able to upset or disturb stratification of the gas layers adjacent 40 the piston top has been absorbed within the gases Y inside thevalve chamber, and following the receding piston, these gases ow through the throat 52 to fill up the cylinder space according to the principle of continuity. 'I'he air is normally introduced to the cylinder in a precompressed state and preferably after intercooling down to a temperature of about 100 F. (560 F. Abs.).

'- cation of the bodies of air and air-fuel mixture,

such stratification is readily maintained during the succeeding compression and power strokes. As shown in Fig. 2, the combustible mixture has been compressed at the end. of the compression stroke into the ignition and'combustion chamber 06, with' the body of pure air underlying the corn bustion mixture below the imaginary dividing line 86, in the clearance space 62. The temperature of both layers of compressed gas is raised during the compression stroke toan absolute temperature of about 1000 F. as a result of substantially adiabatic compression.

During the compression stroke a'small portion of the combustible mixture isforced into ignition cell 80, which isso constructedl'tht it remains in a substantially red hot condition throughout a complete operating cycle; or a glow bar or spark plug 88 (Fig. 2) may be disposed at 70 the end of the cell 80 for the purpose of igr'iiting Y the .combustion mixture compressed into the cell at substantially the top dead center position 84 of the piston 58.

After ignition, the combustible mixture in 75 chamber 00 starts to expand at the beginning oi' the power stroke, the front wave of the body of expanding gases assuming substantially the position outlined by the imaginary line |00 in Fig. 2. This expansion continues as Ishown in Figl 1, driving the piston 58 toward its. bottom dead center position, thev stratification interface between the expanding products of combustion and the pure air assuming substantially the position of the imaginary dotted line |02. The curvature assumed by this interface |02 will vary with variations in the area ratios of the throat 52 and cylinder 80;*and with variations in the volumetric ratlos of the combustion spaces inside valve chamber 06 and cylinder clearance space 62. It will of course be appreciated that the imaginary lines designated 84, 86, |00 and |02 in Figs. land 2 are intended toindicate the position of the interface between th'e airand gas strata within the cylinder, as such interface would be outlined when viewed in vertical cross section. AThere is no difficulty in maintaining such stratification in either horizontally or vertically disposed cylinders, over so short a period as is available for each individual -cycle of high speed engines. Such curved gas interfaces are commonly illustrated by experiments on acoustical vibrations wherein the gas layers oscillate at very h'igh frequencies. However the piston oscillations in engines operating at the highest rotational speeds develop gas vibrations very much below the frequencies of sound.

As shown in Fig. 1, the considerable expartsion in volume of the ignited and burning gases which form the upper gas layer in the cylinder and chamber 6B, effects additional compression of the air forming the lower gas layer, and since the original ignition and expansion largely takes place within a chamber 65 and connecting throat 52 having a cross-sectional area normally smaller than that of the cylinder proper, the resulti ing expansion of hot gases into that zone of the cylinder previously occupied by the air forces the air outwardly as well as downwardly into closer contact with the cylinder walls 60 and the piston 58 (Fig. 1). Thus the compressed pure air below the interface |02 Fig. 1 functions as an insulating and heat absorbingcushion preventing direct contact between the combustion products and cylinder walls and piston, and the otherwise Wasted heat is absorbed into the air instead of being lost to the walls by radiation, convection, and conduction during this rst power stroke.

According to the present invention the first power stroke is conducted with a distinct and very hot core of combustion products and with a relatively cool ambient air envelope, as against standard procedure wherein a substantially homogeneous mixture of burned gases and unburned air is in direct contact with the Walls. Due to the poor heat conductivity of gases in general, very large differences in temperature can and will be maintained between the excess airand burning gases during individual power strokes. `Thus the excess air envelope in the cylinder of an engine operating-onvthe cycle of the present invention is not heated as much as the same proportion of excess air weight would be heated in a Diesel engine, for example, operating with a homogeneous cylinder mixture of the same air-fuel ratio. Furthermore, when the air component of the charge is precompressed and intercooled before its introduction to the cylinder, the compact body of excess air is present inside the cylinder in a cooler state, and because of the larger temperature gradient thereby existing between the air and burning gases, the air cushion can accept and return immediately as power in excess over the compression work, much of the heat radiated from the hot burning gas core, permitting very little heat transfer to the cylinder walls.

Such mechanism o'f heat exchange within the total gaseous cylinder charge may be utilized advantageously either to produce an indicator card of greater area, or preferably to produce the same size of indicator card area with a fuelV charge smaller to the extent of heat prevented from entering the cooling walls. The core of combustible mixture in this case can be kept either of smaller proportion or of a somewhat leaner composition, assuring better combustion without dissociation, and the puff exhaust gas will not be too hot.

At the end of the third stroke the burned core of combustion products is exhausted from the cylinder by the first puff exhaust, and the original excess air is retained for the fourth, fth and sixth strokes in a sufficiently preheated state from the first power stroke to fill up the cylinder space ai; about atmospheric pressure, or at about exhaust receiver pressure when an exhaust gas turbine is employed.

During the fourth stroke this rariiied air is given the same moderate compression as was applied during the second stroke, with a corresponding moderate adiabatic rise of its temperature level. This time, however, the compressed air charge is finally heated to a compression'and temperature high enough to assure self ignition of solidly injected fuel, since the compression started with the air already well preheated.

The fifth and sixth strokes of the cycle are entirely similar to the power and exhaust `strokes of a standard four cycle engine.

Another important feature of this power cycle is the definite elimination of the detrimentally high peak explosion pressures encountered in modern high speed diesels. Although in the first power cycle the core of the charge is an almost theoretically correct mixture, the overall charge air fuel ratio is lean. The second power stroke operates at a peak pressure substantially the same as that of a moderate gasoline engine cycle; however, its air-fuel mixture must be kept slightly leaner to avoid smoky combustion.

Atthe end of the first power stroke valve opens as the piston approaches bottom dead center.

In Fig. 2 the exhaust valve 10 has been shown in closed position, but when open, this valve permits discharge of the exhaust gases from the cylinder into acollector or gas turbine 50 (Fig. 3) against a back pressure, preferably of about 30 pounds absolute. Thus the lower stratum of air within the cylinder is permitted to expand down to this pressure lever and to occupy substantially the total cylinder space, thereby scavenging the cylinder of combustion products. The exhaust valve is then closed and the air remaining in the cylinder is recompressed to a final pressure which may be substantially two-thirds of the peak pressure developed in the cylinder during the first compression stroke. At the same time the temperature of this air rises to aboutl twice the absolute temperature of the air at the beginning of this second compression stroke. In other words, the temperature of the air after this section of the combustion mixture formed by pressure injection of the second charge of fuel through the nozzle 12.

While the preferred operating cycle contemplates useof a carbureter 16 in the air supply line for the purpose of producing a well-balanced combustible mixture of air and gas which is burned during the first power cycle, it will be appreciated that the combustible mixture for the first power cycle could be produced by employing a fuel injector nozzle such as 12, through which the fuel could be projected into the body of air introduced (preferably compressed and inond compression is such as to allow for self-ignitercooled) .to the cylinder during the second stage of the air intake stroke. The use of the carbureter 16 is preferred to insure the most efficient mixing of the air and fuel which is to be used during the first power stroke.

The apparatus of Fig. 3 has been illustrated to include means whereby the body of air which is admitted to the cylinder for use during the second power stroke may be cooled, While the air which is mixed with fuel for combustion during the first power stroke is admitted to the cylinder Without intermediate cooling. To effect this result, the section of the air pipe 14 Within which is located the intercooler .56 and carbureter 16 is mounted in parallel or shunt with another section of pipe 82 within which there is mounted a carbureter 90. A pair of shuttle valves |06- l08 is mounted in position to control circulation of air from the compressor either through pipe 82 and carbureter 90, or through the intercooler 56 and carbureter 16. As shown, these shuttle valves may be rotatably mounted on a shaft IIO actuated from the engine crank shaft I I2 at a speed which is proper for regulating introduc- -tion of successive proportional volumes of cool fresh air and hotcarbureted fuel-air mixture to the cylinder during the intake stroke. This modification of the preferred apparatus to include the by-pass connection 82 and carbureter together with the shuttle valves |06 and |08 and the actuating mechanism therefor, is particularly adapted to a cycle modification according to which during the first intake stroke a major part of the cycle air is conducted through the intercooler 56 to the cylinder 60, and during the last part of the intake stroke the remaining minor portion of the air passes through the carbureter 90 in a heated state where it is charged with fuel to provide an over-rich mixture. On the compression stroke this over-rich mixture is further heated and may reach a self-ignition temperature at the top dead center position of the piston.

lThe relative proportions of fresh air and airfuelmixture admitted to the cylinder during the first intake stroke may be widely varied. Normally it is preferred to admit about 30 -40% of the air used in the complete cycle as cold fresh airduring the first part of the intake stroke', and during the last part of the intake stroke to admit the balance of the air in an air-fuel mixture containing approximately 60-70% of all of the fuel which is used during the complete cycle.

The type of carbureter 1S, 90 which is illustrated in Fig. 3 is designed particularly for use with a relatively low pressure fuel supply feeding fuel supply valves- 11 and 13 are actuated and timed from a camshaft to open only during the proper period for supplying fuel to the engine .cylinder through the various fuel supply nozzles during the `operating cycle. The fuel supply to carbureter 16 will be cut off when carbureter 90 is used.

In a multi-cylinder engine the present six-.1

stroke cycle process is carried out within twof cylinders, the primary cylinder operating on a;

four-stroke cycle, and a secondary cylinder operating on a two-stroke cycle. In the particular engine illustrated diagrammatically in Fig. 5,

three cylinders are provided, two of which operate on four-stroke cycles as primary cylinders,

while a third cylinder operates on a two-stroke illustrated finishing its compression stroke, while piston |26 in cylinder |22 is shown completing its exhaust stroke. Piston |28 in the single secondary cylinder |30 operates on a two-stroke cycle, and is illustrated in the position assumed at the end of its own secondary compression stroke and the beginning of its power stroke. All three cylinders are.,illustrated as operating on-the same crank angle. However, one primary cylinder always operates on a third stroke of its cycle-while the other primary cylinder is operating on its rst stroke, or in other words, the

primary cylinders operate on cycles which have a 360 crank angle spacing.

The first three strokes of the operating cycle for each of the cylinders |20 and |22 follow substantially the same cycle as for the single cylinder six-.stroke engine previously described. In the engine of Fig. 5, however, each of the cylinders |20 and |22 is provided with side wall air exhaust ports |32 which are-uncovered by the pistons |24 and |26 as the pistons approach bottom dead center position. A pair of conduits or transfer passages |34 communicably connect the side wall discharge ports |32 of primary cylinders |20 and |22 with air inlet ports |36 opening into the combustion end of secondary cylinder |30. Flow of gas through the conduits |34 isregulated by a pair of apertured plunger valves |38 and |40 each operatively associated with one of the conduits |34. The opening and closing of valve |38 is preferably effected from a, cam shaft- |42 in timed relation to the position of piston |24 in cylinder |20; and likewise the opening and closing of valve |40 is eiected in timed relation to the piston |26 in cylinder |22. In other words, valve |38 is opened for a crank angle period of say sixty to ninety degrees during each fourstroke cycle of piston |24 in cylinder |20, and the same is true with respect to valve |40 and the piston in cylinder |22. Valves |38 an d |40 preferably open about 45 crank angle ahead of the bottom dead center position of their corresponding pistons |24 and |26 during the expansion or power stroke of the pistons. Likewise, the valves |238 and |40 are preferably timed to close about 45 crank anglebeyond bottom dead center position of the corresponding piston on the exhaust stroke of the piston. The valves |38 and |40 are of course timed to remain closed during all other portions of the four stroke piston cycle practiced in each of the cylinders |20 and |22.

During the period in which each ofthe valves |38 and |40 remains open, the body of air which forms' the lower layer of gases in the corresponding cylinders |20 and |22 during the power stroke is forced outfrom .the corresponding primary cylinder through the corresponding conduit |34 into the combustion end of the secondary cylinder |30 through air intake ports |36. At the time that vthis transfer of air takes place from one of theprimary cylinders to the secondary cylinder, the secondary piston is passc ing through its bottonl dead center position,- at

the end of the expansion 'or working stroke, and at the beginning of the following compression stroke. Secondary cylinder |30 is illustrated as equipped with a plurality of side wall exhaust ports |44 located in a position approximately corresponding to the position ofy the air discharge ports |32 in the primary cylinders |20 and |22. 4In other words, exhaust ports |44 in cylinder |30 are uncovered by the piston |26 during the period in which the piston is passing through its bottom dead center position. Therefore introduction of air from lone of the primary cylinders into the combustion end of the secondary cylinder |30 serves the double purpose of scavenging cylinder |30 of products of combustion produced therein during the preceding power stroke, and filling the cylinder with preheated air preparatory to the compression stroke of piston |26.

At the end of the secondary compression stroke in cylinder |30 fuel for the secondary power stroke is injected through e. high pressure injection nozzle |46, and on the power stroke ignition .and combustion of the air-fuel mixture takes During the exhaust strokes` place in the cylinder. of the pistons in each of the primary cylinders |20 and |22, the products of combustion remaining in the corresponding cylinder after discharge of the lower layer of'air into the secondary cylinder, are exhausted intothe open atmosphere `or into an exhaust receiver or exhaust turbine |46, preferably against a relatively low back pressure.

As'will be appreciated, each of the primary cylinders |20 and |22 is so constructed as to follow closely in design and operation the single cylinder engine which is illustrated in Figs. 1 and 3. Each of the cylinders |20 and |22 is preferably equipped with an ignition and valve chamber 66 at its combustion end, which chamber corresponds in design and function with the corresponding chamber 66 of the single cylinder engine. Air inlet valves 60 and gas exhaust valves 1 0 are mounted in the valve chambers 66 of each primary cylinder. Air valves 68 and fuel valves 11 function to control the successive admission of pure air and of precarbureted airfuel mixture to the valve chamberjand thence through a throat 52 into the working cylinder proper, during the intake stroke of the piston. Likewise exhaust valves 10 operate to permit outflow of waste combustion gases from the cylinder and valve chamber 66 during the exhaust stroke of the piston, following the closing off of the air discharge ports |32 and connecting conduit |34, within approximately the first 45 movement of the crankoperating the piston beyond bottom dead center on its exhaust stroke.

A design feature of the combustion end of the secondary cylinder |30 consists in having the with the fuel injection nozzle |46 located at the apex of the cone. By this construction highly eiiicient scavenging is assured because the inflowing air builds up a compact and 'stable rotating gas cylinder, growing at a steady rapid rate and moving downwardly to force from the cylinder space gaseous products of combustion produced during the preceding power stroke.

While the secondary cylinder |30 operates on a. two-stroke cycle, this operation is effected without the usual port diiculty experienced in two-cycle engines. In the first place itis only preheated air, and not very hot combustion products, which is to be transferred from cylinders |20 and |22 by way of the ports |32 and admitted through the admission ports |36. Furthermore the exhaust ports |44 are not subjected to severe heat stresses for the reason that the weights of hot gas handled in the secondary cylinder |30 are considerably lower than corresponding values for the usual two-cycle engine.

The engine Which is illustrated in Fig. 5 is designed with the pistons of each of the three cylinders operating on the same crank angle. It will be recognized, however, that the piston of the secondary cylinder need not operate on the same crank angle as the pistons of the primary cylinders, since by reversing the position of this cylinder so that the combustion end of the cylinder is at the lower end of the piston stroke, the piston can be operated at a crank angle spaced 180 in phase from the crank angle common to the pistons of the high pressure cylinders.

Fig. illustrates diagrammatically how the operation of each of the gas flow control valves as well as of the pistons and fuel valves can be effected and timed from the main engine crank shaft |50. Each of the valves 58, 10, 11, |38,

and |40 is actuated from cam shaft |42 by means of connecting rods and cams or eccentrics rotatably connected tothe cam shaft. The cam shaft |42 is in turn driven from crank shaft |50 at half the speed of the crank shaft, by means of a connecting shaft |52 and suitable connecting gearing. Each of the pistons |24, |26, and |28 is connected'directly to the drive shaft by piston and connecting rods, cross heads and cranks. While Fig. 5 includes no illustration of specific means foi` supplying the air and fuel to the primary cylinders of the engine, it will be appreciated that according to the preferred cycle such means would include an air compressor, air intercooler and fuel carburetor 16, preferably arranged substantially in the same relative relation as the corresponding elements 5I, 56, and 16 associated with the single cylinder engine of Fig. 3.

By carryinglout the internal combustion operation in accordance with the preferred six-stroke cycle, burning the fuel supply for one cycle in two power strokes, it is possible to secure eicient combustion without developing excessive pressures within the cylinder on either power stroke, thereby assuring safe operation and normal wear for the engine. By the use of supercharging or precompression of the combustion air, preferably with some intercooling, the engine can be operated with an overall compression ratio lying in substantially the same range as the compression ratios for standard compression ignition engines of the Diesel type, while holding the pressures developed Within the cylinders well within gasoline engine practice. By operating on a cycle which employs precarburetion of the fuel-air charge which is burned during the rst power stroke, substantially 100% combustion efficiency can be assured for this stroke even though ignition` of the mixture is effected by means of a spark or hot spot ignition element. Even the use of the spark or hot spot element during the rstpower stroke has its advantages. In the first place this insures easier starting of the engine as compared to selfignition engines; and in the second place an opportunity is afforded for operating the engine with eflicient combustion during idling, as by cutting out the second power stroke and operating the engine only on one powei` stroke for each six-stroke cycle. Thus by the preferred cycle of the present invention, that portion of the fuel combustion which takes place during the first power stroke develops under conditions closely resembling those existing instandard V gas discharge passage ported out in said cham- 1. In an internal combustion engine. a cylinder bore, a piston mounted for reciprocation in said bore, an ignition and valve chamber at one end of the bore, a throat permanently and communicably connecting the chamber and bore, said throat having a cross-sectional area not less than A of the cross sectional area of the bore, an air and fuel supply inlet and a burned gas discharge passage ported out in said chamber, valves for said inlet and discharge passages, an

igniting element positioned within said chamber,

two air supply pipes communicably connected to said air inlet, a fuel carburetor disposed at an intermediate point in one of said pipes, valves arranged for delivering air and air-fuel mixture to said air inlet alternatively through said air supply pipes, and valve actuating and timing mechanism arranged for operating said valves in timed relation to the engine operating cycle to supplyV air and air-fuel mixture successively to the air inlet during a single air intakev stroke s of the piston.

2. In an internal combustion engine, a cylinder bore, a piston mounted for reciprocation in said bore, an ignition and valve chamber at one end of the bore, a throat permanently and communicably connecting the chamber and bore, said throat having a cross-sectional area not less than one quarter of the cross-sectional area of the bore, lan air and fuel supply inlet and a burned ber, valves for said inlet and discharge passages, an igniting element positioned within said chamber, an aircompressor, a pipe communicably connecting said air compressor and the air inlet, a fuel carburetor disposed in an intermediate portion of said pipe, an intercooler mounted in a section of the pipe arranged as a by-pass around the carburetor, and a pair of valves and actuating mechanism therefor for alternatively connecting said carbureter and intercooler into the pipe leading from the compressor to the air inlet to the valve chamber.

3. In an internal combustion engine, a pair of primary and secondary cylinder bores, a pair oi' pistons, one of which is mounted for-reciproation respectively in each bore, an ignition t tore, a fuel injection vair primary bore, a throat communicably connectingsaid chamber andthe primaryv bore, said '/4 of the cross,- sectional area of the bore. an

a air and fuel inlet passage and a burned gas discharge passage ported out in said chamberfvalves for said inlet and outlet passages movably mounted within said'chamber, an air discharge .pOr-t in the wall of said primary bore at the" end thereof opposite the chamber and in position to be uncovered by the piston at the bottom dead center of its stroke, a valved air-transfer passage and ports communicably connecting the air discharge port of the primary cylinder bore with the ignition endof the secondary cylinder nozzle ported out in the ignition end of the secondary cylinder bore, and a gas discharge port opening into the side wall adjacent the bottom dead center position of the piston in the secondary cylinder bore.

te 'having a cross-sectional area of not less, an

gine comprising la 'combustion cylinder, a pistonj. mounted for' reciprocation therein, an ignition and valve chamber atone end of the cylinder, an air intake portA anda'gas discharge po'rtfor -said chamber, valvesfor said intake and dis charge ports, .an air. compressor, a pair of air 4. Apparatus as deiined in claim 3 in which the air transfer passage and ports opening into the ignition end of the secondary cylinder are arranged to inject' the transferred airV into the secondary cylinder in a direction toward the cylinder head.

5. In an internal com ustion engine, a cylinder bore, a piston mounted for reciprocation in said bore, an ignition and valve chamberat one end of .the bore, a throat permanently and communicably connecting the chamber and bore, an air supply inlet, a fuel inlet, and a burned gas discharge passage all ported ontL in said chamber, valves for such inlets and discharge passage, an

igniting element positioned in said chamber* an air supply conduit communicably connected to said air inlet, a `carburetor disposed at an intermediate point in said air supply conduit, valves arranged alternatively to supply pure air and carbureted with fuel tosaid inlet. through said air supply timing mechanism arranged for valves in timed relation to the engine operating \cyc1e to supply air andiair-fuel mixture successively during a single air intake stroke of the piston.

6. A six-stroke cycle combustion enconduit, and valve actuating and. operating said Vsupply conduits with natively supplying airtc said air intake port, the

valves arranged for altercornpressor, a fuel carbureter mounted in' one `of said air supply conduits,` and valve actuating and timing mechanism arranged for operating o said valves in timed relation to the engine operating cycle to supply air and air-fuel .mixture successively during a single air intake lstroke' of the piston.

7. A six-stroke cycle internal combustionengine comprising a combustion cylinder, a piston mountedffor reciprocation therein, an ignition and valve chamber at `one end` of the cylinder, I an air intake port and a gas discharge port for said chamber, valvesfor said intake and discharge ports, an air supply pipe communicably f connected to said air intake and having a fuel carbureter disposed at an intermediate point thereof, a fuel supply pipe leading to said carbureter, a valve in said fuel supply pipe, and

actuating and timing mechanism for operating said valves in timed relation to the engine oper-` ating cycle to supply ai'r and air-fuel mixture successively and alternatively during a single air intake stroke of the piston. l

8. A` six-stroke cycle internal combustion en` l gine comprising a combustion cylinder, a piston. mounted for' reciprocatic-n therein, an ignition' and valve chamber at one end of the cylinder, an air intake 9017i: and a gas discharge-port for said chamben'va'lves for vsaid intakeand discharge portsga pair'of air supply, conduits with valves arranged for alternatively supplying air froma common source to said air .intake port, a fuel carbureter mounted in one of said vair supply conduits, a fuel injectionv ncmle ported out into said ignition and valve chamber, a valve for controlling supply of fuel to said nozzle, andv4 actuating and timing mechanism arranged to open 'said 'valve only at the end of strokeof saidengine cycle.

JOHANN. ,l 

